Serial data bus protocols such as Inter-integrated Circuits (I2C, or I2C, which notation is adopted herein) protocol and Serial Peripheral Interface (SPI) protocol allow at least one ‘master’ integrated circuit (IC) to communicate with at least one ‘slave’ IC, for example via a bus. I2C, and other communications protocols, communicate data according to a clock period. For example, a voltage signal may be generated, where the value of the voltage is associated with data. For example, a voltage value above x may indicate a logic “1” whereas a voltage value below x volts may indicate a logic “0”, where x is a predetermined numerical value. By generating an appropriate voltage in each of a series of clock periods, data can be communicated via a bus or another communication link.
Some 2D and 3D printing systems include one or more replaceable print apparatus components, such as print material containers (e.g. inkjet cartridges, toner cartridges, ink supplies, build material supplies etc.), inkjet printhead assemblies, and the like. In some examples, logic circuitry associated with the replaceable print apparatus component(s) communicate with logic circuitry of the print apparatus in which they are installed, for example communicating information such as their identity, capabilities, status and the like.
In some examples, these communications utilize I2C communications. In such examples, the master IC may generally be provided as part of the print apparatus (which may be referred to as the ‘host’) and a replaceable print apparatus component would comprise a ‘slave’ IC, although this need not be the case in all examples. There may be a plurality of slave ICs connected to an I2C communication link (for example, containers of different colors of print agent). The slave IC(s) may comprise logic circuitry to perform data operations before responding to requests from logic circuitry of the print system.
In some examples, it may be intended to detect the physical location of slave devices that are attached along a serial bus. It may, for example, be intended that devices such as replaceable print apparatus components occupy a certain designated physical position within a print apparatus. For example, in a printing apparatus with ink supply devices attached to a serial bus, there may be an expected position for, for example, a black cartridge, a yellow cartridge, a cyan cartridge and a magenta cartridge, each of which may have a particular address under a communications protocol. By detecting whether specific ink color cartridges have been misinstalled or swapped, printing with incorrect or intended colors may be prevented. A prior patent disclosure is US patent application publication number US 2011/0029705.